Shortcut Trick
The given ratio sin θ : cos θ = 5 : 12 implies tan θ = 5/12.
Using the standard Pythagorean triplet (5, 12, 13), where Perpendicular = 5 and Base = 12.
The Hypotenuse must be 13.
Since sin θ = Perpendicular / Hypotenuse, the value is 5/13.
∴ The correct answer is 5/13.
Alternate Method
Given: Ratio of sin θ to cos θ is 5 : 12.
Formula: tan θ = sin θ / cos θ and sin θ = P / H.
⇒ sin θ / cos θ = 5 / 12
⇒ tan θ = 5 / 12
⇒ Let Perpendicular (P) = 5k and Base (B) = 12k
⇒ Hypotenuse (H) = √(P2 + B2)
⇒ H = √((5k)2 + (12k)2) = √(25k2 + 144k2)
⇒ H = √(169k2) = 13k
⇒ sin θ = P / H = 5k / 13k = 5/13
This corresponds to Option 2 as provided in the question.
∴ The correct answer is 5/13.
Additional Information
Pythagorean Triplets
Common sets of integers (a, b, c) that satisfy a2 + b2 = c2 include (3, 4, 5), (5, 12, 13), (8, 15, 17), and (7, 24, 25).
Trigonometric Ratios
For an acute angle: sin θ = Opp/Hyp, cos θ = Adj/Hyp, and tan θ = Opp/Adj.
Fundamental Identity
The primary trigonometric identity is sin2θ + cos2θ = 1, which holds for any angle θ.